Periodontal disease refers to pathological conditions of the supporting structures of the teeth. In its many forms it is estimated to affect 75 percent of the adult U.S. population and is the most common cause of tooth loss in persons over the age of 35 years. In 1978 $100 million or approximately one percent of the total U.S. dental bill was spent directly treating periodontal disease. An additional unknown amount was spent on prevention and to replace teeth lost to the disease. A number of approaches have been advocated for its control, ranging from prevention or conservative therapy to use of antibiotics or surgical procedures. Controversy exists as to the method of choice. This study is designed to evaluate the cost-effectiveness of periodontal disease control. The specific aims are to identify and define alternative approaches for control of periodontal disease; estimate their costs and effectiveness through a review of the literature and survey of experts; develop an outcome measure of effectiveness (Quality-Adjusted Tooth Years) through elicitation of patient values placed on various levels of oral health status; and to recommend a rational distribution of resources for periodontal disease control. The methods of the proposed study consist of five stages. The first is a review of the literature to define the problem, identify viable alternative approaches for the control of periodontal disease, and estimate their costs and relative effectiveness. The second stage will structure the cost-effectiveness model and identify needed data. In the third stage a questionnaire will be developed and sent to recognized experts in periodontology to obtain estimates of parameters needed for the analysis. The fourth stage of the study will utilize patient interviews to estimate the value of periodontal disease control and avoidance of tooth loss. The final stage will be the cost-effectiveness analysis. Policy recommendations will be made for the distribution and utilization of resources for the control of periodontal disease considering costs, effectiveness, and patient values.